As a treatment method for sleep apnea syndrome, such that an airway is obstructed and becomes apnea during sleep, CPAP (Continuous Positive Airway Pressure) treatment is known, in which gas for breathing pressurized in the range from 392 to 1961 Pa is continuously supplied to the nostrils of a patient when sleeping, so that the airway of the patient is expanded, and thus the patient breathing is assisted.
For CPAP treatment, a breathing gas supply apparatus is used, which has a function for generating gas for breathing by pressurizing the air. Gas for breathing generated by the breathing gas supply apparatus is supplied through a flexible hose to a breathing mask. The breathing mask, as an example is described in Patent Document 1, is configured to cover the nostrils of the patient who uses the breathing mask (hereinafter, the “user”). And the user is supplied with gas for breathing by wearing the breathing mask when sleeping.
To achieve the intended effect of therapy by CPAP treatment, it is important to ensure that gas for breathing does not leak out of the breathing mask. Therefore, it is required that the breathing mask be in close contact with the environs of the nostrils and fixed in that condition for a long term. To meet such a requirement, various methods have been proposed. For example, in Patent Document 1 and Patent Document 2, a headgear-style wearing tool is described. The headgear-style wearing tool fixes the breathing mask by straps fasten around the head of the user. A cold mask-style wearing tool described in Patent Document 3 fixes the breathing mask by loop-shape elastic bands latching around ears of the user. Further, in Patent Document 2, there is a description of a breathing mask which is configured so that an angle of the above mentioned wearing tool attached to the breathing mask is adjustable. This breathing mask has an angle adjustment mechanism which is configured so that a connecting portion with the wearing tool is configured to be rotatable, and an angle of the breathing mask relative to the environs of the nostrils of the user is adjusted, and thus the degree of closeness of contact of the breathing mask is enhanced.
In addition, if humidity contained in gas for breathing or the breath of the user is condensates on the inner walls of the breathing mask and water drops drip onto the face of the user lying on the back, the user is needlessly wakened. Therefore, methods to prevent this have been proposed. For example, a breathing mask described in Patent Document 4 has the outer shell (frame) which is dual structured, and a heat insulating air layer between the inner and the outer walls of the breathing mask. By this means, the temperature of the inner walls is maintained higher than the temperature of the outer walls, and the condensation is suppressed.
Further, when the user lies on the side with the breathing mask worn, if the flexible hose is crushed by his body, supply of gas for breathing is inhibited and the treatment is interfered. To prevent this, for example, there is a description of a breathing mask in Patent Document 5, which has on the frame a rotatable L-shape tube to be connected with the flexible hose. By this breathing mask, the user can direct the flexible hose to the direction such that the concern of the flexible hose being crushed under the user's body who lies on the side is smaller, and thus crushing of the flexible hose can be prevented.